src/java.base/share/classes/java/util/jar/Attributes.java

@@ -511,11 +511,11 @@
         /**
          * Computes the hash value for this attribute name.
          */
         public int hashCode() {
             if (hashCode == -1) {
-                hashCode = name.toLowerCase(Locale.ROOT).hashCode();
+                hashCode = String.CASE_INSENSITIVE_HASHER.applyAsInt(name);
             }
             return hashCode;
         }
 
         /**